Manipulating Spatial Processing in a Audio System

ABSTRACT

A vehicle audio system that includes a source of audio signals, which may include both entertainment audio signals and announcement audio signals, speakers for radiating audio signals, and spatial enhancement circuitry comprising circuitry to avoid applying spatial enhancement processing to the announcement audio signals.

BACKGROUND

This disclosure relates to manipulating spatial processing in a vehicleaudio system that is used to radiate entertainment audio andannouncement audio.

SUMMARY

In one aspect, a vehicle audio system includes a source of audiosignals, which may include both entertainment audio signals andannouncement audio signals, speakers for radiating audio signals, andspatial enhancement circuitry comprising circuitry to avoid applyingspatial enhancement processing to the announcement audio signals. Thespatial enhancement circuitry may apply no spatial processing operationsto the audio signals received from the source if there is announcementaudio content in the audio signals received from the source. The spatialenhancement circuitry may include first alternately selectable circuitryfor applying the spatial enhancement processing to the audio signals,second alternately selectable circuitry for applying no spatialenhancement processing to the audio signals, and circuitry for selectingthe audio signals from the first or second alternately selectablecircuitry based on the presence of announcement audio signal in thecombined audio signals. The spatial enhancement circuitry may includecircuitry for separating the audio signals from the audio signal sourceinto entertainment audio signals and announcement audio signals,circuitry for applying spatial enhancement processing to theentertainment audio signals, and circuitry for combining the processedentertainment audio signals and the announcement audio signals. Thesource of audio signals may include a source of front audio signals thatmay contain front announcement audio signals, hereinafter referred to asfront audio signals, and a source of rear audio signals that may containrear announcement audio signals, hereinafter referred to as rear audiosignals and the audio system may further include front spatialprocessing circuitry including first alternately selectable frontcircuitry for applying the spatial enhancement processing to the frontaudio signals, second alternately selectable front circuitry forapplying no spatial enhancement processing to the front audio signals,and circuitry for selecting the audio signals from the first or secondalternately selectable front circuitry based on the presence ofannouncement audio signal in the front audio signals. The audio mayfurther include rear spatial processing circuitry that includes firstalternately selectable rear circuitry for applying the spatialenhancement processing to the rear audio signals, second alternatelyselectable rear circuitry for applying no spatial enhancement processingto the rear audio signals, and circuitry for selecting the audio signalsfrom the first or second alternately selectable circuitry rear based onthe presence of announcement audio signal in the rear audio signals. Thespatial enhancement circuitry may apply spatial enhancement processingto the entertainment audio signals and not apply spatial enhancementprocessing to the announcement audio signals.

In another aspect, a method for operating a vehicle audio systemincludes receiving audio signals that may contain announcement audiosignals; if the received audio signals do not contain announcement audiosignals, the method includes applying spatial processing to the receivedaudio signals; and if the received audio signals include announcementaudio signals, the method does not apply spatial processing to theannouncement audio signals. The method may include, if the receivedaudio signals include announcement audio signals and entertainment audiosignals, applying spatial processing to the entertainment audio signals.

In another aspect, a vehicle audio amplifier includes an input terminalfor receiving audio signals that may include announcement audio signalsand spatial enhancement circuitry containing circuitry to avoid applyingspatial enhancement processing to the announcement audio signals. Thespatial enhancement circuitry may apply no spatial processing operationsto the received audio signals if the received audio signals includeannouncement audio signals. The spatial enhancement circuitry mayinclude first alternately selectable circuitry for applying the spatialenhancement processing to the combined audio signals, second alternatelyselectable circuitry for applying no spatial enhancement processing tothe combined audio signals; and circuitry for selecting the audiosignals from the first or second alternately selectable circuitry basedon the presence of announcement audio signals in the combined audiosignals. The spatial enhancement circuitry may include circuitry forseparating the combined audio signals into entertainment audio signalsand announcement audio signals, circuitry for applying spatialenhancement processing to the entertainment audio signals, and circuitryfor combining the processed entertainment audio signals and theannouncement audio signals. The input terminal may include an inputterminal for receiving front audio signals that may include announcementaudio signals, hereinafter referred to as front input terminal and aninput terminal for receiving rear audio signals which may includeannouncement audio signals, hereinafter referred to as rear inputterminal. The amplifier may further include front spatial processingcircuitry including first alternately selectable front circuitry forapplying the spatial enhancement processing to the front audio signals,second alternately selectable front circuitry for applying no spatialenhancement processing to the front audio signals, and circuitry forselecting the audio signals from the first or second alternatelyselectable front circuitry based on the presence of announcement audiosignal in the front audio signals, and the audio system may furtherinclude rear spatial processing circuitry including first alternatelyselectable rear circuitry for applying the spatial enhancementprocessing to the rear audio signals, second alternately rear selectablecircuitry for applying no spatial enhancement processing to the rearaudio signals, and circuitry for selecting the audio signals from thefirst or second alternately selectable rear circuitry based on thepresence of announcement audio signal in the rear audio signals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a vehicle with an audio system;

FIG. 2 is a block diagram of elements of the audio system in bypassmode;

FIG. 3 is a block diagram of elements of the audio system in extractionmode; and

FIG. 4 is a block diagram of elements of an audio system with twospatial processing paths

DETAILED DESCRIPTION

Referring to FIG. 1, a vehicle audio system 100 includes a head unit 120coupled to an amplifier 140 through an amplifier input terminal 380. Theamplifier 340 is in turn coupled to speakers 302, 303, 304, 306, and 308through output terminals such a terminal 390. In this particularexample, the head unit 120 provides a user with AM/FM tuning, and CDplayback capability. The head unit 120 also is able to receive audiosignals from external sources 125 a, 125 b providing audio to a vehiclelistening space. The external audio sources may include digital musicplayers (i.e. mp3, CD, DVD) 125 a, portable navigation device 126 b,satellite radio receiver, and/or other sources. In addition toentertainment audio, the head unit 100 provides non-entertainment,announcement audio. Announcement audio may include navigation systemaudio instructions, vehicle chimes, enunciated announcements, cell phonechimes/rings, cell phone conversation, and other non-entertainment audiosources.

The head unit 120 provides to amplifier 140 both the entertainment audioand announcement audio when present. The amplifier 140 include circuitryfor applying spatial enhancement processing to the audio signal toenhance the presentation of entertainment audio inside the vehiclecabin. Spatial enhancement can include adding channels, such as centeror surround channels, or other processing that can affect the spatialcharacteristics of the audio system, for example by “widening” the soundstage by modifying inter-aural crosstalk.

When announcement audio is present in a combined audio signal, spatiallyenhancing the combined entertainment and announcement audio signal canlead to undesirable audible artifacts. For example, the resulting audiopresentation may include distorted sound, or bleeding of theannouncement audio into entertainment audio. Similarly, the spatialenhancement processing could direct the pertinent audio signal so thatthe perceived source is in an illogical direction in relation to alistener's location.

In one particular example, a vehicle chime for reminding the car'soccupants to fasten their seatbelt may sound as if it comes from therear of the vehicle if certain spatial enhancement processing is appliedto the signal. If this chime comes from the rear instead of thedashboard, occupants may be confused as to the meaning of the climebecause most people are accustomed to warning/reminder chimes comingfrom the dashboard area of the vehicle. Misdirected signaling can beparticularly concerning when audio signal is intended as a reminder orwarning for the driver of a vehicle.

To reduce such audible artifacts the amplifier 140 contains circuitrythat avoids applying to the spatial processing operations toannouncement audio.

The head unit 120 also includes fader controls (not shown) that permit auser to control the relative volume between the front (302, 303, 304)and rear speakers (306, 308). For example, the user can manipulate thefader control to direct audio to be faded to the rear speakers only.However, in some implementations, the amplifier 140 directs announcementaudio to the appropriate speaker to maintain the intended location ofthe announcement audio despite the fader setting. For example, if a aDVD movie is playing for children in the rear seat, a parent may fadeadjust the fade control so that the entertainment audio is directedcompletely to rear speakers (306, 308). However if a cellular phoneconnected to (or integrated within) the entertainment system 100 sends aring chime signal to the amplifier 340, the amplifier 340 will presentthe ring chime in one or more of the front speakers (e.g., speaker 302,303 and/or 304).

The processing of announcement audio can be done in at least two ways: abypass mode and an extraction mode.

For example, as shown in FIG. 2 an amplifier 140′ in bypass modeincludes two branches, 320 a, b. An audio signal received from the headunit 120 is processed in parallel in both branches. Branch 320 a appliesspatial processing (e.g., spatial processing described in U.S. Pat. No.7,016,501) and branch 320 b applies no spatial processing. A crossfader330 is coupled to both branches and selects audio from branch 320 a or320 b based on an indication from a control signal from the head unit120 on control signal line 370 as to the presence (or absence) ofannouncement audio.

The crossfader 330 also may process the selected signal so thattransition from selection of one branch to another is smooth. The outputmatrixer then directs the audio signals to the appropriate speakers.

As shown in FIG. 3, an amplifier 140″ in extraction mode includes anannouncement audio extractor 310 that extracts announcement audio fromthe signal received from the head unit. The remainder of the originalsignal (that is, the entertainment audio signal) is processed by spatialprocessor 360. The announcement audio is then summed back into thespatially processed entertainment audio signals at output matrixer 350.Audio signals are then directed to the associated speakers. In someimplementations, the announcement audio is directed to associatedspeakers downstream from the application of fader settings, so thatannouncement audio is radiated properly irrespective of fader settings.In extraction mode, the speakers 302, 303, 304, 306, and 308simultaneously radiate the spatially processed entertainment signals andthe non-spatially processed announcement audio signals or radiate thespatially processed entertainment audio signals.

In systems in which the head unit transmits a front audio signal and arear audio signal and inserts announcement audio in the front audiosignal only, the announcement audio extractor 310 may compare the frontaudio signal and the rear audio signal and extract the differencebetween the front audio signal and the rear audio signal to determinethe announcement audio content.

Referring to FIG. 4, a head unit 120′ is coupled to two processing pathsthat are each similar to the processing path illustrated in FIG. 2. Afront audio signal (i.e., the audio signals intended for speakerslocated in the front portion of the automobile's cabin) is processedseparately from the rear audio signal (i.e., the audio signals intendedfor speakers located in the rear portion of the cabin). Each pathincludes a separately controlled crossfader (360R, 360F) so that, forexample, the front crossfader 360F can select the spatially processedsignal from signal path 320 a-F based on the absence of announcementaudio as indicated by the absence of an indication on front control line370F. Similarly, the rear crossfader 360R could select the bypassedsignal from signal path 320 b-R based on the presence of announcementaudio as indicated by the presence of an indication on control line370R. An amplifier that contains two implementations of the spatialpathway permits announcement audio to be separately radiated by bothfront and rear speakers, with less likelihood of misdirection. The useof multiple pathways permits greater flexibility in system design andallows for more announcement audio radiation source points. For example,some automobile warning systems have sensors that detect if there is anobject near the rear of the automobile if the automobile is in reversegear. The warning noise can come from one or both of the rear speakers,providing an audible cue of the presence of the object near the rear ofthe automobile.

Though the elements of several views of the drawing may be shown anddescribed as discrete elements in a block diagram and may be referred toas “circuitry”, unless otherwise indicated, the elements may beimplemented as one of, or a combination of, analog circuitry, digitalcircuitry, or one or more microprocessors executing softwareinstructions. The software instructions may include digital signalprocessing (DSP) instructions. Unless otherwise indicated, signal linesand terminals may be implemented as discrete analog or digital signallines or terminals, as a single discrete digital signal line or terminalwith appropriate signal processing to process separate streams of audiosignals, or as elements of a wireless communication system. Some of theprocessing operations maybe expressed in terms of the calculation andapplication of coefficients. The equivalent of calculating and applyingcoefficients can be performed by other analog or digital signalprocessing techniques and are included within the scope of this patentapplication. Unless otherwise indicated, audio signals or video signalsor both may be encoded and transmitted in either digital or analog form;conventional digital-to-analog or analog-to-digital converters nay beomitted in some figures. Audio signal processing (for exampleequalization) that does not significantly affect the spatialcharacteristics of the audio is omitted from the figures. For simplicityof wording “radiating acoustic energy corresponding to entertainmentaudio signals” may be referred to as “radiating entertainment audiosignals”, and “radiating acoustic energy corresponding to announcementaudio signals may be referred to as “radiating announcement audiosignals.”

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other embodiments are within the scope of the followingclaims.

1. A vehicle audio system comprising: a source of audio signals, whichmay include both entertainment audio signals and announcement audiosignals; speakers for radiating audio signals; and spatial enhancementcircuitry comprising circuitry to avoid applying spatial enhancementprocessing to the announcement audio signals.
 2. A vehicle audio systemaccording to claim 1, wherein the spatial enhancement circuitry appliesno spatial processing operations to the audio signals received from thesource if there is announcement audio content in the audio signalsreceived from the source.
 3. A vehicle audio system according to claim1, wherein the spatial enhancement circuitry includes: first alternatelyselectable circuitry for applying the spatial enhancement processing tothe audio signals; second alternately selectable circuitry for applyingno spatial enhancement processing to the audio signals; and circuitryfor selecting the audio signals from the first or second alternatelyselectable circuitry based on the presence of announcement audio signalin the combined audio signals.
 4. A vehicle audio system according toclaim 1, wherein the spatial enhancement circuitry comprises circuitryfor separating the audio signals from the audio signal source intoentertainment audio signals and announcement audio signals; circuitryfor applying spatial enhancement processing to the entertainment audiosignals; and circuitry for combining the processed entertainment audiosignals and the announcement audio signals.
 5. A vehicle audio systemaccording to claim 1, wherein the source of audio signals comprises asource of front audio signals that may contain front announcement audiosignals, hereinafter referred to as front audio:signals, and a source ofrear audio signals that may contain rear announcement audio signals,hereinafter referred to as rear audio signals, the audio system furthercomprising: front spatial processing:circuitry comprising firstalternately selectable front circuitry for applying the spatialenhancement processing to the front audio signals; second alternatelyselectable front circuitry for applying no spatial enhancementprocessing to the front audio signals; and circuitry for selecting theaudio signals from the first or second alternately selectable frontcircuitry based on the presence of announcement audio signal in thefront audio signals, the audio system further comprising rear spatialprocessing circuitry comprising first alternately selectable rearcircuitry for applying the spatial enhancement processing to the rearaudio signals; second alternately selectable rear circuitry for applyingno spatial enhancement processing to the rear audio signals; andcircuitry for selecting the audio signals from the first or secondalternately selectable circuitry rear based on the presence ofannouncement audio signal in the rear audio signals
 6. A vehicle audiosystem according to claim 1, wherein the spatial enhancement circuitryapplies spatial enhancement processing to the entertainment audiosignals and does not apply spatial enhancement processing to theannouncement audio signals.
 7. A method for operating a vehicle audiosystem comprising: receiving audio signals that may contain announcementaudio signals; if the received audio signals do not contain announcementaudio signals, applying spatial processing to the received audiosignals; if the received audio signals include announcement audiosignals, not applying spatial processing to the announcement audiosignals.
 8. A method according to claim 7, further comprising: if thereceived audio signals include announcement audio signals andentertainment audio signals, applying spatial processing to theentertainment audio signals.
 9. A vehicle audio amplifier comprising: aninput terminal for receiving audio signals that may include announcementaudio signals; and spatial enhancement circuitry containing circuitry toavoid applying spatial enhancement processing to the announcement audiosignals.
 10. A vehicle audio amplifier according to claim 9, wherein thespatial enhancement circuitry applies no spatial processing operationsto the received audio signals if the received audio signals includeannouncement audio signals.
 11. A vehicle audio, amplifier according toclaim 9, wherein the spatial enhancement circuitry includes: firstalternately selectable circuitry for applying the spatial enhancementprocessing to the combined audio signals; second alternately selectablecircuitry for applying no spatial enhancement processing to the combinedaudio signals; and circuitry for selecting the audio signals from thefirst or second alternately selectable circuitry based on the presenceof announcement audio signals in the combined audio signals.
 12. Avehicle audio amplifier according to claim 9, wherein the spatialenhancement circuitry comprises circuitry for separating the combinedaudio signals into entertainment audio signals and announcement audiosignals; circuitry for applying spatial enhancement processing to theentertainment audio signals; and circuitry for combining the processedentertainment audio signals and the announcement audio signals.
 13. Avehicle audio amplifier according to claim 9, the input terminalcomprising an input terminal for receiving front audio signals that mayinclude announcement audio signals, hereinafter referred to as frontinput terminal and an input terminal for receiving rear audio signalswhich may include announcement audio signals, hereinafter referred to asrear input terminal, the amplifier further comprising: front spatialprocessing circuitry comprising first alternately selectable frontcircuitry for applying the spatial enhancement processing to the frontaudio signals; second alternately selectable front circuitry forapplying no spatial enhancement processing to the front audio signals;and circuitry for selecting the audio signals from the first or secondalternately selectable front circuitry based on the presence ofannouncement audio signal in the front audio signals, the audio systemfurther comprising rear spatial processing circuitry comprising firstalternately selectable rear circuitry for applying the spatialenhancement processing to the rear audio signals; second alternatelyrear selectable circuitry for applying no spatial enhancement processingto the rear audio signals; and circuitry for selecting the audio signalsfrom the first or second alternately selectable rear circuitry based onthe presence of announcement audio signal in the rear audio signals.